Ear :: Viral enzyme to prevent ear infection

Parents might one day give their children a weekly treatment with a nasal spray of virus enzymes to prevent them from getting a severe middle ear infection, based on results of a study done in mice by investigators from St. Jude Children’s Research Hospital and The Rockefeller University, in New York.

Such a treatment would avoid the use of antibiotics, thus eliminating the problem of antibiotic resistance. A report on this study appears in the March issue of the online journal “PLoS Pathogens.”

Middle ear infection, also called acute otitis media, is an inflammation of the middle ear space. About half of all children carry Streptococcus pneumoniae, the bacteria that cause acute otitis media. These bacteria migrate from the nose and throat to the middle ear after an initial influenza virus infection paves the way.

The investigators based their treatment on the ability of viruses called phages to break out of bacteria they infect by using a special enzyme to destroy the cell walls.

The success of the new treatment, which uses a phage enzyme called lysin to kill S. pneumonia, suggests that the strategy could significantly reduce the incidence of acute otitis media in the United States. More than 24 million cases are now diagnosed each year, despite the use of vaccines against S. pneumoniae.

“Lysin also appears to hold promise for preventing the secondary pneumonia caused when a person infected with S. pneumoniae is subsequently infected with the influenza virus, said Jonathan McCullers, M.D., associate member in the Infectious Diseases department at St. Jude. McCullers is first author of the “PLoS” paper.

The investigators demonstrated that lysin can eliminate these bacteria from the ear using mice developed at St. Jude that represented the first such model in which acute otitis media develops in a similar way that it develops the disease in children. The mice were treated by purified lysin that was prepared in the laboratory of Vincent A. Fischetti, Ph.D., a professor and co- head of the Laboratory of Bacterial Pathogenesis and Immunology at The Rockefeller University. He was assisted by Jutta M. Loeffler, postdoctoral associate. Fischetti is senior author of the “PLoS” paper.

“The nasal spray may eventually be used weekly during flu season to keep a person free of Streptococcus pneumoniae or after infection with the flu virus,” said Fischetti. “This might truly be a case in which an ounce of prevention would be worth a pound of cure.”